The lightning protection system comprises an interconnected
network of air terminals, conductors, and grounding electrodes that form a
conducting grid outside the interior space of the vessel. The protective zone provided by the air
terminals (four rail-mounted air terminals and the two outriggers) gives
coverage over all deck area, with the possible exception of a crew member on
the bow pulpit, and interior space. Since the VHF antennas are not included in the protective zone, a
transient voltage surge suppressor (TVSS) is highly recommended for each
antenna cable. This TVSS is not included in the present protection
package. Down conductors are
preferentially routed externally to all wiring, plumbing and occupied regions. A continuous loop conductor constructed from
aluminum strip is connected to the down
conductors, the handrail, the metal superstructure, outriggers, aluminum sub
flooring, and other large metallic fittings. Grounding is provided via eight Siedarc electrodes, distributed around
the hull, two 0.5 ft2 immersed grounding strips near the base of the
outriggers, and a Ward's ground plate at the stern. All grounding electrodes are preferentially
installed above and near the waterline.

Major features are summarized in the diagrams in Appendices
1 and 2. Appendix 3 is a copy of Figure
18 from ABYC Standard E-11 showing a common connection for DC ground, AC
ground, cathodic bonding ground, and lightning bonding ground. Appendix 4 gives instructions for lug
terminations.

Any antenna is at risk of damage even if it is inside the protective
zone. While it is impractical to
ensure the survival of the antenna itself, protective measures are highly
recommended to reduce the likelihood of damage caused by the voltage surge. As a precaution, a transient voltage surge
suppressor (TVSS) should be installed in each antenna coax as close as possible
to the point where the coax enters inside the lightning protection system. Connect the grounding lug of the TVSS to the
closest conductor in the lightning protection system and place at least two
tight coils in the coax on the other side of the TVSS.

The loop conductor is constructed predominantly from the
1" aluminum strip provided. It
encircles the whole boat in a continuous loop as shown in Appendix 1. The most convenient height for this is at the
main floor level where it is interconnected with the aluminum flooring
beams.

Pass the aluminum strip outside the flooring beams screwing
directly into the beams as frequently as practical. See "Connections" below for
connection details. Continue this strip
forward at the same level to the bow.

In order to avoid a "U" around the aft cockpit
gate, drop the loop level to just below the floor level of the cockpit and
continue around the stern. This may be
constructed of either aluminum strip or 2AWG insulated battery cable
(supplied). If battery cable, use a
bimetallic connector for the point between the aluminum strip and the lug,
attempting to cover both the lug and aluminum strip connections with the wet
type heat shrink provided (see Section 4.4.5 below).

Appendices 1, 2, and Figure 3‑2 show suitable
paths for lightning down conductors. All
down conductors should be made from either the 1" aluminum strip provided
or insulated 2 AWG tinned copper battery cable terminated with the heavy duty
lugs supplied by Marine Lightning Protection (see Appendix 4 for termination
details). In general, the preferred
route is the most direct path from air terminal to the closest grounding
electrode with all direction changes by means of as smooth a curve (large
radius of curvature) as possible. However, right angled connections between different conductors is
acceptable.

The outriggers, metal handrails, and metal superstructure
are used as conductors in the lightning protection system, as shown in Figure 4‑1. Connections
should be made at the ends of these fittings as indicated. Appendix 2 shows the interconnections between
the lightning protection system components and these fittings.

All connections to grounding strips and Siedarc electrodes
are to be made from 2AWG marine-grade insulated battery cable. This cable is already supplied with any
electrodes that have a parallel connection. These cables may be lengthened using either similar cable or aluminum
strip connected through the supplied bimetallic connectors. See Section 4.4.5 below for details of this connection between tinned copper
and aluminum

All lugs are intended for 2AWG cable and have a 3/8" diameter hole. (NOTE: AN exception is the lugs that come attached
to the daisy-chain Siedarc electrodes, which have a ¼" hole. These should ONLY be used for connecting
cable to the electrode and HStrip in the daisy-chain configuration explained in
the Installation Directions for the HStrips.) The manufacturer's directions for connecting cable to lug are included
in Appendix 4. For better electrical
continuity, 0.1-0.3 ml of PenetroxE joint compound should be injected into each
lug before inserting the stripped cable. Also, application of heat shrink (with a 1.5" cable overlap) is
highly recommended to improve resilience and further impede moisture intrusion. PenetroxE should also be applied between
surfaces that are to be connected before attachment.

There are two ways to make a connection through the deck or
topsides to a stainless fitting:

a. Threaded hole inside fitting

This method is useful in a stanchion or vertical post where
a hole can be made internally. This is
demonstrated in the photos below. The
fitting is first removed from the deck, a 3/8-16 thread is tapped into the
fitting, and a thrudeck connector with threaded stud is screwed into the
fitting. Use threadlock to ensure a permanent
attachment. Drill a 7/8" diameter
hole through the deck or topside wall in line with the connector and insert the
connector into this hole when reattaching the fitting. The electrical connection can then be made
inside the boat using the 3/8-16 thread inside the connector.

b. Threaded hole in flange

In an alternative to a above, the threaded hole can be made through
an exposed surface in the same way and capped with an acorn nut, embedded with
marine sealant, to ensure a watertight attachment, as shown below.

c. Though bolt through fitting flange

This method does not give as good a connection as the above two but may be the only option if the fitting cannot be removed. Basically it is identical to the above except that the hex stud is not used and the through-bolt is either aluminum (e.g. TCA15) or tinned brass (e.g. TC15) . On the inside of the deck the connection is made to a ½" hex stud.

Use a ½" standoff stud for superior connections to the
main loop. Drill a 3/8" diameter hole through the aluminum strip, insert the stainless bolt through the
aluminum (1" diameter) washer and the strip, and then screw on the ½"
aluminum stud. Connections can then be
made using the stainless washer (7/8" diameter), lock washer, and jam nut. If the connecting conductor is copper alloy
or tinned copper use a bimetallic connector (see next section).

Use the bimetallic connector (BMC) provided. If the connection is to be made to the loop conductor, connect the
bimetallic connector to an aluminum stud attached directly to the loop via a 3/8" hole through the loop strip. If the
connection is to be made as a butt connection to an aluminum strip, drill a 3/8"
hole about ¾ " from the end of the strip, feed a stainless bolt first
through an aluminum washer, then the strip, then the aluminum end of the
bimetallic connector, a stainless washer, lock washer and secure with the jam nut. Encase both connecting screws in the heat
shrink provided in the BMC package to exclude moisture.

Splices between cables can be made by terminating each cable
in a lug at the point of the splice, stacking the lugs together and securing
with a through bolt and nut. When
splicing into a main down conductor, assure that the down conductor lugs are at
180 degrees and the lug on the spliced cable is angled down as much as possible
to avoid U-shaped loops. Cover all
splices with wet-type heat shrink or waterproof tape. Alternatively, 2- 3- and 4-way splices can be made with S-2A, Splice-3 and Splice-4 respectively. These all come with tinned hardware for galvanic compatibility.

Electrode positioning is illustrated in Appendices 1 and 2
and Figure 3‑2 . Two
flush-head electrodes with parallel connectors are installed near the bow, and
two more below the down conductor at the front of the cabin. Two flush-head electrodes with daisy-chain
connections are installed amidships beneath the outriggers. The connection to these is continued to the
HStrips on both sides. Two mushroom-head electrodes with parallel connectors
are installed where near the stern. See Appendices 1,3,4 and 6. Generally, each electrode should be installed above the stationary
waterline and below the lowest flange of any nearby plumbing through
hulls. In addition, the two stern
electrodes should be positioned so that the cable from the electrode to the
HStrip is perpendicular to the strip. Each electrode cable is attached to the bonding loop by the shortest
path possible, with the lug at 90 degrees to the bonding strap, and using the
same 3/8" machine bolt to attach the electrode
cable,and corresponding down conductor to the bonding strap. See Installation Instructions
for Siedarc electrodes for details.

Place each HStrip below the waterline at a depth where it
will be immersed during all normal modes of operation. The connection from the bonding strap to each
HStrip should be made by as direct a path as possible from the strap, through
the daisy-chain Siedarc electrode, to one of the HStrip bolts. See Installation
Instructions for HStrip grounding strips for details.

The lightning protection system described in this document
is fundamentally consistent with Chapter 8 in the National Fire Protection
Association Standard NFPA780-2008. Any
departures are considered by the author to be improvements over this revised
standard. In general, lightning
protection systems are limited by the current state of knowledge and no
implication is intended that this, or any, protection system will prevent
damage or injury.